With the development and proliferation of technologies such as Voice Over Internet Protocol (VoIP), an increased amount of telephony and related functionality is being made available over electronic networks such as the Internet. A telephony application can provide functionality over an electronic network that is common for traditional public switched telephone networks (“PSTNs”). Such functionality can include call forwarding, voice mail, conference calls, call blocking, televoting, call screening, telephone number portability, toll free calls and Freephone, prepaid calling, account card calling, virtual private networks (e.g. family group calling or enterprise “telephony” networks on PSTN), Centrex service (virtual private branch exchange (PBX)), private number plans (with numbers remaining unpublished in directories), short numbers and short codes, Universal Personal Telecommunication service (a universal personal telephone number), mass-calling services, prefix free dialing from cellphones abroad, seamless multimedia messaging service (MMS) access from abroad, reverse charging, home area discounts, premium rate calls, call distribution based on various criteria associated with a call, location based routing, time based routing, proportional call distribution (e.g. between two or more call centers or offices), and call queueing.
The functionality can be implemented in what is known in the industry as an Intelligent Network (IN). The Intelligent Network can use a variety of protocols, sometimes using a layered approach where the application layer is referred to as the Intelligent Networks Application Part (INAP), and sometimes using a less-layered protocol such as the Transaction Capabilities Application Part (TCAP). One standard for the IN protocols is the Customized Applications for Mobile networks Enhanced Logic (CAMEL), which allows increased functions for mobile phones. A Camel Application Part (CAP) can be layered on top of TCAP so that additional functions can be added to TCAP.
For European Telecommunications Standards Institute (ETSI) Wireline or old wireless networks, the following protocols are used: INAP, INAP Capability Set One (CS-1), INAP CS-1+ (an Ericsson variant), and SINAP (a Siemens variant). For North America, the Advanced Intelligent Network (AIN) is often used by carriers such as Qwest Communications, AT&T, EMBARQ® Wireless, and Rogers Communications. For Global System for Mobile communications (GSM) and Universal Mobile Telecommunication Systems (UMTS), the following protocols are typically used: CAP v1 to v4, INAP CS-1+, and SINAP 5m/7m. For networks using wireless code division multiple access (CDMA)/1x, Wireless Intelligent Networking (WIN) phase 1 (IS-771) and WIN phase 2 (IS-826) are often used. Second and third tier operators, operating in locations such as Mexico and Brazil, sometimes do not yet have a fully capable Intelligent Network; therefore, Integrated Services digital network User Part (ISUP) and Telephone User Part (TUP) protocols are also relevant in those localities.
A Service Control Point (SCP) typically is used to carry out the above and other functions that are not directly related to the routing of messages through the network. An SCP allows control at the service level of a network so that a service logic can drive the protocol to provided one of the services above. In general, the service logic is protocol specific and developed and executed directly as a manipulation of the protocol specific exchanges. The service logic is built for one specific IN (i.e. a well-defined protocol). In integrated telephone networks, these servers are mostly implemented as functions in the telephone exchange, but in more open networks such as Internet protocol (IP) telephony networks based on the SIP (session initiation protocol) protocol, Next Generation Networks (NGN), and Internet protocol Multimedia Subsystem (IMS), these are often separate computers which comprise the server.
In one approach, an SCP server supports the execution of service logic of applications such as call processing and routing, call-termination, messaging, and subscriber-independent, or subscriber-dependent, applications. The SCP includes service logic which implements the behavior desired by the operator, i.e., the services. During logic processing, additional data and capabilities required to process a call may be obtained from the Service Control Function (SCF). Examples of the applications provided on an SCP (as service logic) include such capabilities as local number portability, free-call routing resolution, conference bridge services, and unified messaging. The application/telephony service can be provided by service chaining on calls (incoming or outgoing).
Telephony applications (i.e. telephony/IN/PSTN service on service control points) are generally one of two types: those that are signaling only, and those that involve media manipulation. The former are often related to a routing resolution, including functionality such as local number portability, free-call routing, and other services where the dialed number must be translated to a routable address. Examples involving media manipulation include conference bridge applications, interactive voice response (IVR), etc., which are services with which many business professional are familiar. The call steps for such an example include the following. A user calling in on a pre-published number. The dialed number is translated into an IP address and named the endpoint of the application server, and the call is routed to that endpoint. The application server connects to the media server, instructing the media server to play a greeting and collect the conference number. The media server returns a conference number, and the application server instructs the media server to play a prompt to collect the authorization number. If the digits collected are correct, the application server tells the media server to move this call to a particular conference bridge.
Another example is a prepaid SCP in which the service is a prepaid service for a call or messaging. In such a service, the system checks the user's subscription and also manages the user's ratings and balances.
Such approaches, however, retain aspects of the PSTN versions but do not take full advantage of the new electronic environment.